This invention relates to a process for applying and bonding a solid lubricant on a substrate to thereby impart lubricity to the substrate.
The lubrication of parts which are in moving contact with each other is necessary in order to maintain and protect the integrity of the respective parts and thereby permit continued efficient functioning of the apparatus in which the moving parts reside. A common lubricant which is effective in many applications is natural or synthetic oil. Vehicle engines, electric motors, and the like, typically employ oil to achieve required lubricity.
Oil, however, is not effective above certain temperatures since it will decompose and lose its lubricating qualities. As a result, solid lubricants have been developed for use in high temperature applications where more conventional lubricants are not adequate. Fluoride salt components such as barium fluoride and calcium fluoride, for example, are recognized as highly effective solid lubricants at high temperatures and moderately effective at room temperature. However, the application and bonding of such solid lubricants on a substrate such as a ceramic material which ultimately will be in moving contact with another substrate is presently rather complicated. In particular, such present application and bonding generally requires that the lubricant be applied to the substrate at very high temperatures so that the lubricant will be in a molten state or will be sintered during application. The lubricant essentially infiltrates the substrate, and the application may be performed under vacuum conditions. Despite these rather stringent and demanding techniques, the solid lubricants still suffer expected degradation when the substrate is placed in moving-contact use. Thus, when the lubricant is worn away, the substrate either must be discarded or the same complicated application procedure must be repeated to renew original lubricity. Solid lubricant films also have been deposited using sputtering technology, ion implantation, high-temperature force of a stick of solid lubricant against a substrate, water-slurry spray followed by firing in hydrogen, vacuum impregnation, plasma spray, and the like. As is apparent, all of these techniques likewise require specialized and generally complicated procedures.
It is therefore a primary object of the present invention to provide a process for applying and bonding a solid lubricant on a substrate at room temperature without requiring thermal activity whatsoever. Another object of the present invention is to provide a process for applying and bonding a solid lubricant on a substrate wherein fine solid lubricant particles are deposited on the substrate and a subsequent burnishing procedure distributes and bonds the lubricant particles on the substrate. Yet another object of the present invention is to provide a process wherein lubricity of a substrate can be effectively renewed after a portion of a previously-applied solid lubricant has worn away. These and other objects of the present invention will become apparent throughout the description thereof which now follows.